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Crystal Structure of Bag6-Ubl4A Dimerization DomainCrystal Structure of Bag6-Ubl4A Dimerization Domain
Structural highlights
FunctionUBL4A_HUMAN Component of the BAT3 complex, a multiprotein complex involved in the post-translational delivery of tail-anchored (TA) membrane proteins to the endoplasmic reticulum membrane. TA membrane proteins, also named type II transmembrane proteins, contain a single C-terminal transmembrane region. The complex acts by facilitating TA proteins capture by ASNA1/TRC40: it is recruited to ribosomes synthesizing membrane proteins, interacts with the transmembrane region of newly released TA proteins, and transfers them to ASNA1/TRC40 for targeting.[1] Publication Abstract from PubMedBCL2-associated athanogene cochaperone 6 (Bag6) plays a central role in cellular homeostasis in a diverse array of processes and is part of the heterotrimeric Bag6 complex, which also includes ubiquitin-like 4A (Ubl4A) and transmembrane domain recognition complex 35 (TRC35). This complex recently has been shown to be important in the TRC pathway, the mislocalized protein degradation pathway, and the endoplasmic reticulum-associated degradation pathway. Here we define the architecture of the Bag6 complex, demonstrating that both TRC35 and Ubl4A have distinct C-terminal binding sites on Bag6 defining a minimal Bag6 complex. A crystal structure of the Bag6-Ubl4A dimer demonstrates that Bag6-BAG is not a canonical BAG domain, and this finding is substantiated biochemically. Remarkably, the minimal Bag6 complex defined here facilitates tail-anchored substrate transfer from small glutamine-rich tetratricopeptide repeat-containing protein alpha to TRC40. These findings provide structural insight into the complex network of proteins coordinated by Bag6. Bag6 complex contains a minimal tail-anchor-targeting module and a mock BAG domain.,Mock J, Chartron JW, Zaslaver M, Xu Y, Ye Y, Clemons WM Jr Proc Natl Acad Sci U S A. 2014 Dec 22. pii: 201402745. PMID:25535373[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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